1. Field of the Invention
This invention relates generally to the field of RF channelized receivers, and more specifically pertains to a method for real-time detection of multiple RF pulses of varying amplitude and frequency and a compact, low power parameter encoder and channelized receiver capable of simultaneous, real-time detection of multiple RF pulses over a wide RF bandwidth.
2. Description of the Related Prior Art
Electronic warfare systems are used on modern military ships and aircraft. An electronic warfare search receiver is used to detect opposing force radar emissions. The receiver searches the range of frequencies in which the RF emissions are likely to occur, and detects and analyzes the nature of the signals. By determining the characteristics of the received signals, the user knows the nature and location of the threat.
In a tactical or strategic environment, the density and diversity of the emissions in the RF spectrum is quite large and is expected to increase. With previous detection and monitoring wideband search receivers it is difficult or impossible to successfully monitor such RF emissions. For example, some existing wideband receiver designs employ a simple threshold detector that requires the incoming signal to attain a certain amplitude before it is recognized as a true signal apart from the ordinary RF background noise. These receivers are incapable of differentiating between high amplitude short duration and low amplitude long duration pulses, when they are first detected. With the existing designs, it is entirely possible that the first RF pulse received will effectively prevent detection of the second RF pulse, from another emitter, during the presence of the first pulse. Thus, the first emission source may be identified while the second source is, in effect, masked.
Channelized receivers offer high probability of intercept even in highly dense environments. They provide instantaneous wide bandwidth detection while maintaining high dynamic range, high frequency resolution and direction finding capabilities. This is accomplished by division of the entire wide bandwidth into a number of narrower bandwidths, and parallel processing of each narrow bandwidth in a separate receiver. Therefore, channelized receivers have generally been impractical prior to the mid 1990s because the RF and digital circuitry required for twenty to one hundred detectors is too large and heavy and consumes too much power for tactical platforms.
The radar detection and identification systems should be able to provide information in real time. However, the conventional systems which are able to operate in real time can accurately work only within a limited range of radar pulse parameters, and the sensitivity of the systems decreases rapidly as the parameters depart from the selected range. Further, the systems that must provide high sensitivity have required use of large programmable computers and thus could not be placed upon typical airborne platforms. Moreover, even with the fastest supercomputers, the conventional systems can operate in real time only in a limited bandwidth, usually in the order of 20 MHz.
One existing pulsed signal detection device uses a software-implemented multilevel matched detection filter matrix. Although it has to run on supercomputers, it can only process a very narrow IF bandwidth. This high sensitivity system with "Matched Detection Matrix" (MDM) needs 127 filters plus second pass processing to complete signal characterization on only 20 MHz bandwidth. The system described here is cascaded to provide 1 GHz blocks of real-time pulse parameterization.
Therefore, there is a need for an efficient, small, lightweight, low power channelized receiver with single-pass, real-time characterization processing to meet the needs of future tactical aircraft, helicopters and surveillance platforms and for upgrading the electronic warfare capabilities of existing aircraft. Such a receiver should overcome the limitations of conventional systems in speed and sensitivity as well as bandwidth. The system should also be programmable and should have the ability to eliminate most of the spurious signals while maintaining a high probability of intercepting real signals.
This application is an improvement of the channelized receiver architectures described in U.S. Ser. No. 438,232, filed on May 9, 1995 entitled "Parameter Encoder Architecture", now U.S. Pat. No. 5,572,213, issued Nov. 5, 1996; U.S. Ser. No. 08/109,804, filed on Aug. 20, 1993 entitled "Instantaneous Parameter Measuring Receivere", now U.S. Pat. No. 5,451,956, issued Sep. 19, 1995; and U.S. Ser. No. 08/443,174 filed May 3, 1995 entitled "Advanced Parameter Encoder with Dual Integrated Pulse Present Detection and Channel/Sector Arbitration", now U.S. Pat. No. 5,550,546 issued Aug. 27, 1996, which is a continuation application of Ser. No. 08/154,906, filed Nov. 19, 1993, now abandoned.